Seriously, does anyone really believe they "accidentally" put all of the 3D horsepower into the iPod Touch / iPhone without intending it to be a great gaming platform?
The iPod Touch has always been good for games. But it wasn't always positioned as a game player. Or a pocket computer. Now it is.
Perhaps they thought it might take off that way but weren't sure and the cost of the 3D horsepower compared to lesser capabilities was low enough that it made sense to include it for the added flexibility in being able to position the device whereever the market told them it should go?